Behavioral changes in whitefly (Bemisia tabaci) influenced by Tomato leaf curl New Delhi virus infection and plant volatile emission in bitter gourd (Momordica charantia)

Abstract

Bitter gourd (Momordica charantia L.) is a tropical vine which belongs to the family Cucurbitaceae and is widely cultivated in southeast Asia. The bitter gourd is significantly affected by tomato leaf curl New Delhi virus (ToLCNDV), a single stranded DNA virus with bipartite genome which belongs to the Begomovirus genus and family Geminiviridae. The virus is transmitted by whiteflies (Bemisiatabaci) cryptic species complex. When the virus infects plants, it has the ability to significantly alter the phenotypes of its host plant, including the production of plant volatile compounds. A free choice bioassay was conducted between healthy and ToLCNDV infected bitter gourd plants with a Y-tube olfactometer to study the preferences and infestation behaviour of B. tabaci on bitter gourd. Significantly, more viruliferous whiteflies were attracted towards healthy plants and non-viruliferous whiteflies were attracted towards infected plants that could facilitate virus spread. Volatile organic compounds released from healthy and ToLCNDV infected plants were analysed with gas chromatography – mass spectrometry (GC-MS) which revealed subtle qualitative/quantitative changes. Specifically, the compound 1-Heptadecene (4.86%) is present in healthy bitter gourd plants and 2,5-Bis (5-tert-butyl-2-benzoxazolyl) thiophene (6.94%), Methyl cis-11-icosenoate (3.25%) and lactic acid (4.22%) are present in virus infected bitter gourd plants. The results show that the progression of ToLCNDV in bitter gourd is correlated with functional changes in volatile profile which alters the behavioural responses of whitefly. Additionally, the study depicts that the altered chemistry of the host plant modifies the recruitment and dispersal patterns of whiteflies in ways that facilitate virus transmission.